HAND-HELD RECIPROCATING TOOL

Abstract: Hand tool with an apparatus housing (2) in which there are movably mounted a rotary portion (8) and a reciprocating slide (10) non-rotatably but displaceably mounted in the housing, said slide serving as a holder for a tool (12). The rotary portion (8) has an oblique shaft (32) with a rolling bearing device (36) mounted thereon, which converts the rotation of the rotary portion into a reciprocating movement of the displaceable portion (10). The rolling bearing device (36) comprises one or two rolling bearings with outer ring surface areas, via which the bearing device is in direct driving contact with a driver element (52) at the end of the displaceably mounted slide (10). The driver element (52) is in direct engagement with the outer rings (48, 50) of the bearing device via opposite lateral surfaces (54, 56).

Description: HAND-HELD RECIPROCATING TOOL The present invention relates to a hand tool with an appara¬ tus housing in which two main portions are movably mounted, viz a rotary portion which is mounted in the housing by means of one or more bearing means, and a portion, which is non- rotatably but displaceably mounted in the housing, is driv- ingly connected to the rotary portion, and is disposed to perform a reciprocating movement in its longitudinal direc¬ tion as well as serving as a fixing means for a working tool, the rotary portion having a shaft oblique relative to the rotational axis of the rotary portion, on said oblique shaft there being mounted a motion transmitting means connected to an adjacent portion of the displaceable portion, said motion transmitting means transmitting, in the manner of a wobbler, the rotational movement of the rotary portion into a reci- procating movement of the displaceable portion. State of the art Hand tools of the above mentioned type as previously known, see e.g. US A 2 824 455 and US A 4 114 270, which describe a portable electrically driven hand saw and a hand-held appara¬ tus for sawing slaughter-house products. In the hand-held electric saw described in US A 2 824 455, the motion is transmitted between the motor-driven rotating portion and the reciprocating portion (in which the saw-blade is fixed) by motion transmitting means. These motion trans¬ mitting means consists of an arm element engaging the reci¬ procating portion, said element being mounted on the oblique crank with the aid of a ball bearing. The arm element con¬ sists of an annular housing surrounding the ball bearing with a housing portion projecting radially from the ball bearing in which there are solidly mounted a shank with a spherical head which engages in an engagement portion on the underside of the reciprocating part. A significant disadvantage of such a motion transmitting means (between the rotary portion and the reciprocating portion) is, however, that the motion transmitting means extends significantly radially from the oblique shaft. This is because the arm element housing surrounding the ball bearing with the projecting housing portion, takes up in this context a significant space between the rotary part and the reciprocating part. These two parts can therefore not be mounted as close together as would be desirable in order to minimize the dimensions of the hand tool apparatus housing. Especially when a hand-held power tool of the type in ques¬ tion is to be used for polishing, sanding, filing and similar operations in confined spaces, and when the place to be worked is limitedly accessible or has small dimensions, it is essential that the dimensions, especially the transverse dimensions (the diameter) , of the apparatus housing be kept down as much as possible. Purpose of the invention The present invention therefore is intended to further deve- lope hand tools of the type described by way of introduction, and to provide a hand tool, the apparatus housing of which has a small transverse dimension (maximum diameter)", so that the hand tool will be easily handled. The design should also be simple and reliable, and in parti- cular the motion transmitting means should be compact and consist of few structurally simple machine elements which can be of standard type. The hand tool should also be constructed so that the compo- nents subjected to wear should be few and easily replaced. The moving parts should further be so constructed and assemb¬ led that they engage without any undesirable play, thus eliminating rattle. The moving parts should also be able to be easily lubricated or be provided with the required lubri¬ cation upon assembly. Description of the invention The above purposes are achieved effectively according to the invention by virtue of the fact that the motion transmitting means is a rolling bearing device mounted on the oblique shaft and comprising one or two rolling bearings, said bear- ing device having outer ring surface areas via which the device is in direct driving contact with the end of the adjacent portion of the displaceable portion, that the dis¬ placeable portion has in the area of said end an end section with a flat lateral surface and an essentially circle seg- ment-shaped cross section, at the end of said end section there being a preferably tooth-like driver element projecting from the flat lateral surface and arranged in direct engage¬ ment with the outer ring(s) , said driver element having opposite lateral surfaces by means of which it is in direct contact with the outer ring surface areas of the bearing device cooperating therewith. The basic idea of the invention can thus be said to be that the reciprocating displaceable portion, by means of a drive element in the form of a laterally directed end projection, is in direct driving contact with the surface areas ' of the outer ring(s) of the respective rolling bearing forming the rolling bearing device. This design completely eliminates the need of a surrounding housing or annular means about the rolling bearing in ques¬ tion. By directly utilizing the outer ring of the rolling bearing(s) for drive transmission to the driver element of the displaceable portion provides a very simple (few compo- , nent parts) motion transmitting mechanism. In the design selected, the space requirement for the motion transmitting means (i.e. the rolling bearing/bearings) is also minimized. This means in turn that relatively large bearings can be used in the motion transmitting chamber of the apparatus housing without making the apparatus housing excessively large. The relation between the dimensions of the rolling bearing device and the mass, which must be moved/accelerated in the motion transmission, can thus also be improved over previously known designs. In the attached dependent claims, there are specified further developing features of suitable embodiments of the invention. The displaceable portion is suitably a slide with, firstly, a forward round slide portion, secondly, an intermediate por¬ tion (with a non-round cross section) which extends to the end section with a flat lateral surface. By virtue of the intermediate portion, the slide is non-rotatably mounted in a non-rotatable bearing sleeve in the apparatus housing. The intermediate portion suitably consists of a slide portion defined by a cylindrical lateral surface and a flat surface, with a cross section in the form of a circle segment. The bearing sleeve has at its end, a slide guide portion coopera¬ ting with the intermediate portion of the slide with a flat guide surface. By virtue of the fact that the flat surface of the intermediate portion is in contact with this guide sur¬ face, the slide is prevented from rotating in the bearing sleeve. In order to minimize the risk of wear and heating caused by friction of the round slide portion of the slide, the bearing sleeve can be provided with a special lubricant chamber, which surrounds the round slide portion. Suitable lubricant, such as oil, can be inserted into the lubricant chamber via a radial channel through the bearing sleeve. A particularly simple embodiment of the rolling bearing device is achieved if it consists of a pair of preferably single-row ball bearings, which are held tightly together side by side with a spacer ring between them on the oblique shaft. This spacer ring creates an annular space between the outer rings of the bearings, into which the driver element of the reciprocating portion can engage. The two ball bearings used in this embodiment can be of wellknown standard type, making the design inexpensive. An alternative, also very simple, embodiment of the rolling bearing device is achieved if it quite simply consists of a preferably two-row ball bearing, which is secured, by means of a pressure washer bearing against the inner ring of the bearing on the oblique shaft. In this case, the outer ring of the ball bearing is provided with a circumferential engaging groove for the driver element of the reciprocating portion. In order to avoid unnecessary inertial forces and vibrations when operating, it is advisable to arrange the oblique shaft at the end of the rotating portion in such a manner, and that the rolling bearing device be mounted on the oblique shaft in such a manner that the center of mass of the bearing device will lie at the point of intersection of the longitudinal axis of the rotating portion and the longitudinal axis of the oblique shaft. Short description of the drawings The invention will now be described and explained further below with reference to several examples shown in the accom¬ panying drawings of a hand tool according to the invention. Figure 1 shows a longitudinal section through a first embodi¬ ment of the hand tool according to the invention, Figure 2 shows a cross section along the line II-II in Fig 2, Figure 3 shows in partial longitudinal section and on a lar¬ ger scale, the area of engagement between the rol- ling bearing device and the driver element of the displaceable portion which is engaged therein, in an embodiment similar to that shown in Fig 1, Figure 4 shows a view from below of the driver element accor¬ ding to Fig 3, Figure 5 shows a cross section along the line V-V in Fig 4, and Figure 6 shows finally a longitudinal section through a se¬ cond embodiment of the hand tool according to the invention. Description of the examples Reference is now made to the first embodiment of the hand tool according to the invention shown in Figures 1 and 2. This hand tool comprises an apparatus housing 2 consisting of a forward portion 4 and a rear portion 6 connected thereto. In the apparatus housing 2 there are rotatably mounted, on the one hand, a rotary portion 8 and, on the other hand, a portion 10 drivingly connected to the portion 8 and serving as an attachment means for a working tool, e.g. a file 12. The shaft of the file 12 is fixed in a bore 11 in the portion 10 by means of a lock screw 13 which is screwed into a fixing head at the end of the portion 10. The rotary portion 8 is mounted in the house portion 6 by means of a rolling bearing 14, in this case a single-row ball bearing. The rotary por¬ tion 8 is imparted rotation by a drive means (not shown) of conventional type, e.g. an electric motor or other drive means. The portion 10 is non-rotatable, but is displaceably mounted in a bearing sleeve 16 fixed in the apparatus hous- ing. The displaceable portion 10 is disposed to be able to perform a reciprocating movement in its longitudinal direc¬ tion in the housing 2. As can be seen in Figure 1, the dis¬ placeable portion 10 is made as a slide comprising, firstly, a front round slide portion 18 and, secondly, an intermediate portion 20 connected thereto. This intermediate portion extends to the end section 22 of the slide 10, which has a flat lateral surface 24 on the bottom. The intermediate portion 20 has, as can be seen in Figure 2, a non-round cross section and has a flat surface 26 on the bottom. The inter- mediate portion 20, which in this case is a slide portion with a circle segment cross section, has at its top a cylind¬ rical surface and a flat surface 26 at the bottom. The bear¬ ing sleeve 16 has, at its end facing the end section 22 of the slide, a slide guide portion 28 cooperating with the flat lower surface 26 of the intermediate portion 20 and having a flat upper guide surface 30. By virtue of the fact that the flat surface 26 of the intermediate portion 20 is in contact with the guide surface 30 of the bearing sleeve 16, the slide 10 is non-rotatably mounted in the bearing sleeve 16, which is in turn non-rotatably mounted in the housing portion 4. In order to reduce friction between the slide 10 and the bearing sleeve 16, the bearing sleeve can be provided with a chamber 17 containing lubricant and which surrounds the round slide portion 18. As can be seen in Figure 1, the rotary portion 8 has at its righthand end as seen in Figure 1 a shaft 32 obliquely direc- ted at an angle α relative to the longitudinal axis 34 of the rotary portion 8. On the shaft 32 there is mounted a motion transmitting means 36 drivingly connected to the end section 22 of the slide 10, said oblique shaft being mounted in a motion transmitting chamber 38 in the apparatus housing 2. This motion transmitting means 36 converts, in a manner similar to a wobbler, the rotation of the rotary portion 8 into reciprocating movement of the slide 10. In the embodiment shown in Figure 1, the rolling bearing device 36 consists of a pair of single-row ball bearings 40 and 42, which are held tightly, with an intermediate spacer ring 44, side by side on the oblique shaft 32. The spacer ring 44 creates an annular space 46 between the ball bearings 40 and 42 and between their outer rings 48 and 50. In order to produce the reciprocating movement of the slide 10, the slide has at its end section 22, at the end of the flat lateral surface 24, a driver element 52 projecting straight out from the surface 24, which in the manner of a tooth engages in the annular space 46 between the outer rings 48,50. The driver element 52 thus stands with both its oppo¬ site side surfaces 54 and 56 in direct contact with the cooperating adjacent surface areas of the side surfaces on the outer rings 48 and 50 of the bearings 40,42. By making the tooth-like driver element 52 thin (in the longitudinal direction of the slide 10, see Figure 4), it is possible to make the driver element 52 engage the space 46 without any play relative to the outer rings 48,50, regard¬ less of the momentary rotational position of the bearing device 36. The absence of play in the engagement eliminates undesirable rattling. For the "bent" lateral surfaces 54 and 56, the transitional area between their respective bevelled halves should be made with a radius of curvature R (see Figure 4) . The transitional areas on both sides of the ele¬ ment 52 can then be parts of a circular cylindrical or sphe¬ rical surface. Wear tests have provided very good results. Small radial movements (with sliding friction) between the driver element 52 and the outer rings 48 and 50 of the bearings produce very small losses, which contributes to the high efficiency. It should thus be possible to use small, light power sources. Both Figures 1 and 3 show the slide 10 with the driver ele¬ ment 52 in one end position. As is particularly evident from Figure 3, there will be a lateral displacement of the outer rings 48,50 as a result of the "prying" effect of the element 52. In the type of ball bearings shown in Figure 3, one can calculate that the radius of curvature of the races of the bearings is approximately 10% greater than the radius of the balls of the ball bearing. As can be seen in Figure 3, a contact angle β is obtained between the ball and the race, which is approximately 30°. The balls, in this way, "climb up" the respective races, and this is advantageous for the operation of the bearings. The rolling bearings 40,42 are tightly fixed to the oblique shaft 32 by means of a pressure washer 58 bearing against the inner ring of the bearing 42, said washer 58 being screwed tightly to the oblique shaft 32 by means of the screw 60. Figure 6 shows a longitudinal section through a second embo- diment of the hand tool according to the invention. This embodiment differs from the one shown in Figure 1 primarily in the design of the rolling bearing device 36. The bearing means 14 also differs in this case from that shown in Figure 1, since the bearing means in this case is a two-row ball bearing 62. In other respects, the embodiment according to Figure 6 completely agrees with that in Figure l, and there¬ fore the rest of the components of the hand tool have been provided with the same reference numerals as in Figure 1. These components, which are known from the embodiment accord- ing to Figure 1, will not be described here since they comp¬ letely agree in their design and function with the components described in connection with Figure 1. The description of the embodiment according to Figure 6 will therefore be essential¬ ly limited to a description of the rolling bearing device 36. The rolling bearing device consists in this case of a two-row ball bearing 64 which, by means of the pressure washer 58 abutting against the inner ring 66 of the bearing, is secure¬ ly mounted on the oblique shaft 32 by means of the screw 60. In the outer ring 68 of the ball bearing 64, there is in this case a circumferential engagement groove 70, in which the slide 10 engages with its driver element 52. The circumferen¬ tial engagement groove 70 in the outer ring 68 corresponds in this case to the annular space 46 of the rolling bearing device 36 in the embodiment of Figure 1. In this case as well, the driver element 52, by its opposite lateral surfaces 54,56, is in direct contact with cooperating surface areas of the outer ring of the bearing device. These surface areas consist in this case of surface areas of the lateral walls of the engagement groove 70. The embodiment according to Figure 6 thus functions in principle in the same manner as the embo¬ diment according to Figure 1. For the two embodiments according to Figures 1 and 6, the oblique shaft 32 is so arranged at the end of the rotary portion 8, and the rolling bearing device 36 is so mounted on the oblique shaft 32, that the center of mass A of the bear- ing device lies at the point of intersection between the longitudinal axis 34 of the rotary portion 8 and the longi¬ tudinal axis 72 of the oblique shaft 32. In general, it is important in a hand tool according to the invention, regardless of the embodiment, that the components which during operation are subjected to wear, i.e. the slide 10, the rolling bearing device 36 and the bearing sleeve 16, be so designed and mounted that they can be easily disassemb¬ led and replaced. These components are also those components which can be made or bought at a relatively low price.

Claims: Claims 1. Hand tool with an apparatus housing in which two main portions are movably mounted, viz a rotary portion (8) which is mounted in the housing by means of one or more bearing means (14), and a portion (10), which is non-rotatably but displaceably mounted in the housing, is drivingly connected to the rotary portion, and is disposed to perform a recipro¬ cating movement in its longitudinal direction as well as serving as a fixing means for a working tool (12) , the rotary portion (8) having a shaft (32) oblique (α) relative to the rotational axis (34) of the rotary portion, on said oblique shaft there being mounted a motion transmitting means (36) connected to an adjacent portion of the displaceable portion (10) , said motion transmitting means transmitting in the manner of a wobbler the rotational movement of the rotary portion into a reciprocating movement of the displaceable portion (10) , c h a r a c t e r i z e d in - that the motion transmitting means is a rolling bearing device (36) mounted on the oblique shaft (32) and comprising one or two rolling bearings (64;40,42), said bearing device having outer ring surface areas via which the device is in direct driving contact with the end of the adjacent portion (22) of the displaceable portion (10) , - that the displaceable portion (10) has in the area of said end an end section (22) with a flat lateral surface " (24) and an essentially circle segment-shaped cross section, at the end of said end section (22) there being a preferably tooth¬ like driver element (52) projecting from the flat lateral surface (24) and arranged in direct engagement with the outer ring (68) or outer rings (48,50), said driver element (52) having opposite lateral surfaces (54,56) by means of which it is in direct contact with the outer ring surface areas of the bearing device cooperating therewith. 2. Hand tool according to Claim 1, c h a r a c t e r i z e d in that the displaceable portion is a slide (10) , comprising, firstly, a forward round slide portion (18) and, secondly, an intermediate portion (20) adjacent thereto and having a non- round cross section, said intermediate portion extending up to an end section (22) with a flat lateral surface (24) , and that the slide (10) , via the intermediate portion (20) is non-rotatably mounted in a bearing sleeve (16) solidly fixed in the apparatus housing (2) . 3. Hand tool according to Claim 2, c h a r a c t e r i z e d in that the intermediate portion (20) is a slide portion with a cross section in the shape of a circle segment and which has a cylindrical lateral surface and a flat surface (26) , and that the bearing sleeve (16) has its end directed towards the rolling bearing device (36) , a slide guide portion (28) cooperating with the intermediate portion (20) of the slide and having a flat guide surface (30) against which the flat surface (26) of the intermediate portion lies, thus prevent¬ ing the slide from rotating in the bearing sleeve. 4. Hand tool according to Claim 2 or 3, c h a r a c t e r ¬ i z e d in that the bearing sleeve (16) has, in its portion housing the round slide portion (18) of the slide, a lubri¬ cant chamber (17) which surrounds the round slide portion. 5. Hand tool according to one of Claims 1 - 4, c h a r a c ¬ t e r i z e d in that the rolling bearing device (36) con- sists of a pair of preferably one-row ball bearings (40,42), which, with an intermediate spacer ring (44) are fi*ed with pretension side by side on the oblique shaft (32) , said spacer ring producing an annular space (46) between the two bearings and thus between their outer rings (48,50), in which space the displaceable portion (10) engages by means of the driver element (52) . 6. Hand tool according to one of Claims 1 - 4, c h a r a c ¬ t e r i z e d in that the rolling bearing device (36) con- sists of a preferably two-row ball bearing (64) which, by means of a pressure washer (58) , bearing against the inner ring (66) of the bearing, is held on the oblique shaft (32), and that there is, in the outer ring (68) of the ball bear- ing, a circumferential engagement groove (70) , in which the driver element (52) of the displaceable portion (10) engages. 7. Hand tool according to one of the preceding claims, c h a r a c t e r i z e d in that the oblique shaft (32) is so arranged at the end of the rotary portion (8) , and the roller bearing device (36) is so mounted on the oblique shaft, that the center of mass (A) of the bearing device lies at the intersection of the longitudinal axis (34) of the rotary portion (8) and the longitudinal axis (72) of the oblique shaft (32) .

Inventors: ERIKSSON ROLF, ERIKSSON, ROLF
Applicants: DENTATUS AB, ERIKSSON ROLF, ERIKSSON, ROLF
Application year: 1994
Main classification: B23D49
IPC codes: B23D51, B27B19, F16H23